Northampton Saints inflicted a torrid afternoon on London Wasps at Adam's Park to go second behind London Irish in the Aviva Premiership.

Wasps' dismal afternoon may have repercussions for England after Riki Flutey had to be helped from the field with a leg injury. The 30-year-old was a near-certainty to start at inside centre for next month's autumn internationals against New Zealand, Australia, Samoa and South Africa.

But the severity of the injury - he was unable to put weight on his leg and looked in considerable pain - will leave England manager Martin Johnson sweating on a fitness bulletin with the All Blacks visiting Twickenham in less than two weeks.

Wasps director of rugby Tony Hanks will be more concerned by the manner in which his team fell apart than the setback to Flutey as Saints climbed to second in the table with a bonus-point victory. Tongan prop Soane Tonga'uiha helped himself to two tries, while Stephen Myler, Chris Ashton and Courtney Lawes also crossed in a traumatising afternoon for the home defence.

Both of Tonga'uiha's tries and the touch down by Lawes came at the end of forward drives through the heart of Wasps' backpedalling pack, while Myler's boot supplied 12 points. The Saints were superb at times with the odd creative flourish playing second fiddle to a power game that embarrassed a Wasps side that was hammered in the collisions all afternoon.

A solitary point is all that separates them from Premiership leaders Irish and today's performance will have alerted their title rivals. Saints owed victory to their big forwards and the likes of Lawes, Tonga'uiha and Brian Mujati proved effective ball carriers right from the start.

Wasps were penalised for collapsing a scrum in front of the posts and were punished by Myler, but the Saints fly-half then missed his second kickable penalty. A simple gameplan was paying dividends for Saints, who repeatedly broke the gainline with assistance from weak first-up tackling by their opponents.

The Premiership title hopefuls took advantage of the lacklustre defending to score their first try, Myler side-stepping his way to the line and then showing strength to surge over in the 17th minute. A second try quickly followed, this time Saints moving 15 metres with a line-out catch and drive that ended when Tonga'uiha was shoved over the line.

Myler nailed the conversion and Wasps suffered a further setback when Flutey was helped from the pitch. There was no respite for the beleaguered home side, who slipped 22-0 behind when Ashton grabbed Myler's grubber and touched down, though there was a hint of offside for the try.

Myler converted the score he set-up and then cancelled out a penalty from Dave Walder with another three points. Wasps were back under the cosh as the second half got under way, their confusion highlighted when bulldozing number eight Andy Powell chipped ahead despite being on the charge.

The bonus point was secured when Tonga'uiha was pushed over for his second, again from a line-out catch and drive, this time five metres out. Myler slotted the touchline conversion and Saints refused to take their foot off the pedal with Lawes claiming the fifth try after another surge through the heart of Wasps' pack. Substitute Ben Jacobs crossed for Wasps after charging down a chip by Ashton, but it was scant consolation to a side that had been crushed with humiliating ease.